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Investigating factors influencing polymer elution and the mechanism controlling the chemical compatibility of GCLs containing linear polymers
https://orcid.org/0000-0002-8635-4613
Abstract A study was conducted to investigate (1) physicochemical factors that influence polymer elution from GCLs containing a blend of bentonite and linear (water-soluble) polymer (LPB GCLs) and (2) the mechanism that controls the chemical compatibility of LPB GCLs when polymer elutes. A series of hydraulic conductivity (k), free swell and viscosity tests were performed on a commercial LPB GCL using DI water, varying concentrations of NaCl and CaCl₂. Comparable tests were also performed on a conventional bentonite (CB) GCL containing the same untreated bentonite and the same physical properties as the LPB GCL. The LPB GCL showed improved swelling and hydraulic performance compared to the CB GCL when permeated with salt solutions. Total organic carbon analysis of the effluents showed that polymer eluted from the LPB GCL regardless of the permeant solution. However, the rate at which polymer eluted increased as the concentration and valence of the dominant cation increased. The rate at which polymer eluted also increased with hydraulic gradient. The mass of polymer retained inside the GCL matrix did not correlate with the k of the LPB GCL. Free swell tests coupled with chemical analysis suggest that, the improved chemical compatibility of the LPB GCL was due to the ability of the polymer to scavenge cations from the solution which allows the bentonite to undergo adequate swelling during the initial hydration period. Analogous to water-prehydrated CB GCLs, the dispersed structure of the bentonite fabric and increased adsorbed water molecules attained during initial swelling controls the k of the LPB GCL when polymer elutes.
Highlights The LPB GCL showed improved swelling and hydraulic conductivity compared to the CB GCL when permeated with salt solutions. Polymer eluted from the LPB GCL regardless of the chemistry of permeant solution (i.e., even when permeated with water). The rate at which polymer eluted increased with concentration and valence of cations in the solution and hydraulic gradient. Hence, the previously hypothesized pore clogging mechanism does not fully explain the improved performance of the LPB GCL. The improved chemical compatibility of the LPB GCL can be attributed to the ability of the polymer to scavenge cations.
Investigating factors influencing polymer elution and the mechanism controlling the chemical compatibility of GCLs containing linear polymers
https://orcid.org/0000-0002-8635-4613
Abstract A study was conducted to investigate (1) physicochemical factors that influence polymer elution from GCLs containing a blend of bentonite and linear (water-soluble) polymer (LPB GCLs) and (2) the mechanism that controls the chemical compatibility of LPB GCLs when polymer elutes. A series of hydraulic conductivity (k), free swell and viscosity tests were performed on a commercial LPB GCL using DI water, varying concentrations of NaCl and CaCl₂. Comparable tests were also performed on a conventional bentonite (CB) GCL containing the same untreated bentonite and the same physical properties as the LPB GCL. The LPB GCL showed improved swelling and hydraulic performance compared to the CB GCL when permeated with salt solutions. Total organic carbon analysis of the effluents showed that polymer eluted from the LPB GCL regardless of the permeant solution. However, the rate at which polymer eluted increased as the concentration and valence of the dominant cation increased. The rate at which polymer eluted also increased with hydraulic gradient. The mass of polymer retained inside the GCL matrix did not correlate with the k of the LPB GCL. Free swell tests coupled with chemical analysis suggest that, the improved chemical compatibility of the LPB GCL was due to the ability of the polymer to scavenge cations from the solution which allows the bentonite to undergo adequate swelling during the initial hydration period. Analogous to water-prehydrated CB GCLs, the dispersed structure of the bentonite fabric and increased adsorbed water molecules attained during initial swelling controls the k of the LPB GCL when polymer elutes.
Highlights The LPB GCL showed improved swelling and hydraulic conductivity compared to the CB GCL when permeated with salt solutions. Polymer eluted from the LPB GCL regardless of the chemistry of permeant solution (i.e., even when permeated with water). The rate at which polymer eluted increased with concentration and valence of cations in the solution and hydraulic gradient. Hence, the previously hypothesized pore clogging mechanism does not fully explain the improved performance of the LPB GCL. The improved chemical compatibility of the LPB GCL can be attributed to the ability of the polymer to scavenge cations.
Investigating factors influencing polymer elution and the mechanism controlling the chemical compatibility of GCLs containing linear polymers
https://orcid.org/0000-0002-8635-4613
Abstract A study was conducted to investigate (1) physicochemical factors that influence polymer elution from GCLs containing a blend of bentonite and linear (water-soluble) polymer (LPB GCLs) and (2) the mechanism that controls the chemical compatibility of LPB GCLs when polymer elutes. A series of hydraulic conductivity (k), free swell and viscosity tests were performed on a commercial LPB GCL using DI water, varying concentrations of NaCl and CaCl₂. Comparable tests were also performed on a conventional bentonite (CB) GCL containing the same untreated bentonite and the same physical properties as the LPB GCL. The LPB GCL showed improved swelling and hydraulic performance compared to the CB GCL when permeated with salt solutions. Total organic carbon analysis of the effluents showed that polymer eluted from the LPB GCL regardless of the permeant solution. However, the rate at which polymer eluted increased as the concentration and valence of the dominant cation increased. The rate at which polymer eluted also increased with hydraulic gradient. The mass of polymer retained inside the GCL matrix did not correlate with the k of the LPB GCL. Free swell tests coupled with chemical analysis suggest that, the improved chemical compatibility of the LPB GCL was due to the ability of the polymer to scavenge cations from the solution which allows the bentonite to undergo adequate swelling during the initial hydration period. Analogous to water-prehydrated CB GCLs, the dispersed structure of the bentonite fabric and increased adsorbed water molecules attained during initial swelling controls the k of the LPB GCL when polymer elutes.
Highlights The LPB GCL showed improved swelling and hydraulic conductivity compared to the CB GCL when permeated with salt solutions. Polymer eluted from the LPB GCL regardless of the chemistry of permeant solution (i.e., even when permeated with water). The rate at which polymer eluted increased with concentration and valence of cations in the solution and hydraulic gradient. Hence, the previously hypothesized pore clogging mechanism does not fully explain the improved performance of the LPB GCL. The improved chemical compatibility of the LPB GCL can be attributed to the ability of the polymer to scavenge cations.
Investigating factors influencing polymer elution and the mechanism controlling the chemical compatibility of GCLs containing linear polymers
Wireko, Christian (author) / Abichou, Tarek (author)
Geotextiles and Geomembranes ; 49 ; 1004-1018
2021-01-27
15 pages
Article (Journal)
Electronic Resource
English
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